Why are some countries rich and others poor? The question, full of childlike curiosity, is the most important in economics. A person’s living standards are mostly determined not by talent or hard work, but by when and where they were born. Historically, most models of economic growth focused on the accumulation of factors of production, labour, capital and, more recently, technology or ideas. The greater the capital stock per worker and the more productive its use, then the richer a country would be. Yet that still left a gap: why did some countries manage to accumulate more of these factors than others?